Merocyanine dyes and photographic emulsions containing them



United States Patent Oiice 2,839,403 Patented June 17, 1958 MEROCYANINE DYES AND PHOTOGRAPHIC EMULSIONS CONTAININ G THEM Edward B. Knott, Harrow,

Kodak Company, New Jersey England, assigner to Eastman Rochester, N. Y., a corporation ot' This invention relates to new merocyanine dyes and photographic silver halide emulsions sensitized therewith. More particularly, this invention relates to new merccyanine dyes containing a 2-thiohydantoin nucleus, having on at least one of the nitrogen atoms thereof a pyridyl or a quinolyl substituent.

Accordingly, it is an object of my invention to provide new merocyanine dyes containing a 2-thiohydantoin nucleus. Another object is to provide methods for making these new merocyanine dyes. Still another object is to provide photographic silver halide emulsions sensiu tized with these new merocyanine dyes. Another object is to provide new intermediates useful in preparing these merocyanine dyes and methods for making these new intermediates, Other objects will become apparent from a consideration of the following description and examples.

The new merocyanine dyes of my invention can advantageously be represented by the following general formula:

wherein R represents an alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-amyl, carboxymethyl, -carboxyethyl, carbomethoxymethyl, carbethoxymethyl, -hydroxyethfyl, -methoxyethyl, allyl (vinylmethyl), benzyl (phenylmethyl), etc. (e. g., an alkyl group of the formula CmH2m+1 wherein m represents a positive integer of from l to 4), d represents a positive integer of from l to 3, `n represents a positive integer of from l to 2, L represents a methine group (i. e., a -CR= group wherein R is a hydrogen atom or a monovalent organic substituent, such as methyl, ethyl, methoxyl, ethoxyl, etc.), Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the 2-thiohy dantoin series, said heterocyclic nucleus having a pyridyl or quinolyl substituent (e. g., 2-pyridyl, 3pyridyl, 4- pyridyl, 6-methyl-2-pyridyl, 4-methyl2pyridyl, Saquinolyl, etc.) attached to at least one of the nitrogen atoms thereof, and Z represents the nonmetallic atoms necessary to complete a. heterocyclic nucleus containing from to 6 atoms in the heterocyclic ring, such as those selected from the group consisting of those ofthe thiazole series (e. g., thiazole, 4-methylthiazole, Sfmethylthiazole, l-phenylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl) thiazole, etc.), those of the benzthiazole series (e. g., benzthiazole, 4-chlorobcnzthiazole, 5-chlorobenzthiazole, 6-chlorobenzthiazole, 7 -chlorobenzthiazole, 4-methylbenzthiazole, 5-methylbenzthiazole, 6-methylbenzthiazole, 5-bromobenzthiazole, 6 bromobenzthiazole, 4-phenylbenzthiazole, 5-pheny1benzthiazole, 4-methoxybenzthiazole, S-methoxybenzthiazole, 6methoxybenzthiazole, S-iodobenzthiazole, -iodobenzthiazole, 4-ethoxybenzthiazole, 5ethoxybenzthiazole, tetrahydrobenzthiazole, 5,6dimethoxybenzthiazo1e,` 5,6-dioxymethylenebenzthiazole, 5hydroxybenzthiazole, 6-hy droxybenzthiazole, etc.), those of the naphthothiazcle lhytlroxyquinoline, etc.),

series (e. g., ot-naphthothiazole (i. e., [2,1]naphthothia Zele), -naphthothiazole (i. e., [1,2]naphthothiazole), 5-methoxy--naphthothiazole, 5-ethoxy--naphthothiazole, 7-methoxy-a-naphthothiazole, 8-methoxyanaphthothia zole, etc.), those of the thianaphtheno-7,6,4,5thiazole series (e. g., 44methoxythiauaphtheno-7,6,4,5thiazole, etc.), those of the oxazole series (e. g., -4-methyloxazole, 5-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazo1e, 4-ethyloxazole, 4,5-dimethyloxazole, 5phenyloxazole, etc.), those of the benzoxazole series (e. g., benzoxazole, 5-chlorobenzoxazole, S-phenylbenzoxazole, S-methylbenzoxazole, 6-inethylbenzoxazole, 5,6-dimethylbenzoxazole, Lt,5-ch'methylbenzoxazole, S-methoxybenzoxazole, 6meth oxybenzoxazole, 5-ethoxybenzoxazole, 6-chlorobenzoxa zole, S-hydroxybenzoxazole, -hydroxybenzoxazole, etc.), those of the naphthoxazole series (e. g., x-naphthoxazole, ,B-naphthoxazole, etc.), those of the selenazole series (e. g., l-methylselenazole, 4phenylselenazole, etc.), those of the benzselenazole series (e. g., benzselenazole, 5- chlorobenzselenazole, 5' -methoxybenzselenazole, 5 hydroxybenzselenazole, tetrahydrobenzselenazole, etc.), those of the naphthoselenazole series (e. g., a-naphthoselenazole, naphthoselenazole, etc.), those of the thiazoline series (e. g., thiazoline, 4-methylthiazoline, etc.), those ol the 2-quinoline series (e. g., quinoline, 3methyl quinoline, S-methylquinoline, 7-methylquinoline, S-methylquinoline, 6-chloroquinoline, 8chloroquinoline, -methoxyquinoline, 6ethoxyquineline, 6-hydroXyquinoline, 8-

those of the 4-quinoline series (e. g., quinoline, -methoxyquinoline, 7methylquinoline, i-methylquinoline, etc.), those of the l-isoquinoline series (e. g., isoquinoline, 3,4dihydroisoquinoline, etc.), those of the 3,3-dialkylindolenine series (e. g., 3,3-dimethylindolenine, 3,3,5-trimethylindolenine, 3,3,7-trimethy1indolenine, etc.), those of the 2-pyridine series (e. g., pyridine, B-methylpyridine, 4-methy1pyridine, 5methylpyri dine, 6metl1ylpyridine, 3,4-dimethylpyridine, 3,5-dimethylpyridine, 3,6-dimethy1pyridine, 4,5-dimethylpyridine, 4,6-dimethy1pyridine, 4-chloropy1idine, S-chloropyridine, 6-chloropyridine, 3-hydroxypyridine, 4-hjydroxypyridine, S-hydroxypyridine, 6-hydroxypyridine, S-phenylpyridine, 4-phenylpyridine, -phenylpyridine, etc.), those of the 4-pyridine series (e. g., Z-methylpyridine, S-methylpyridine, Z-chloropyridine, 3-chloropyridine, 2,3-dimethylpyridine, 2,5-dimethylpyridine, 2,6-dimethylpyridine, 2- hydroxypyridiue, 3hydroxypyridine, etc.), etc.

According to my invention, I provide.` the new dyes Vrepresented by Formula I above wherein d represents 1 by reacting together a cyclammonium quaternary salt selected from those represented by the following general formula:

wherein R, n, and Z each have the values given above. R1 represents an alkyl group (e. g., methyl, ethyl, etc.) or an aryl group (e. g., phenyl, o, m, and p-tolyl, etc.), and X represents an acid anion, e. g., chloride, bromide, iodide, thiocyanate, sulphamate, methylsnlphate, ethylsulphate, perchlorate, benzenesulphonate, p-toluenesulphonate, etc., with a compound selected from those represented bythe following general formula:

III. //Q\ wherein Q has the values given above.

The new dyes of my invention represented by Formula l above wherein d represents 2 or 3 can be prepared by Y n condensing a cyclammonium quaternary salt selected from those represented by the following general formula:

IV. Z

wherein R, n, X, and Z each have the values given above, q represents a positive integer of from 1 to 2, R2 represents an acyl group (e. g., acetyl, propionyl, benzoyl, ete), and R3 represents an aryl group (e. g., phenyl, o-, m, p-tolyl), together with a compound selected from those represented by Formula III.

The condensations of the compounds of Formula lil with those of Formulas II (or 1V) can advantageously be accelerated by heating the reaction mixture, generally temperatures varying from ambient temperature (ca. C.) to the reflux temperature of the reaction mixture being satisfactory. The condensations can be carried out in the presence of an inert solvent, such as pyridine, nitrobenzene, ethanol, n-propanol, isopropanol, n-butanol, etc.

The condensations of the compounds of Formula Ill with those of Formulas Il (or IV) can advantageously be carried out in the presence of a basic condensing agent,

such as the trialkylamines (e. g., triethylamine, tri-npropylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-n-amylamine, ete), N-alkylpiperidines (e. g.,`N-me'thy1piperidine, N-ethylpiperidine, etc.), NJN-dialkylanilines (e. g., N, N-dimethylaniline, diethylaniline,

etc.),etc.

Particularly useful merocyanine dyes selected from those represented by Formula I above comprise those dyes represented by the following general formula:

I Ri

wherein R, n, d, and Z each have the values given above, R4 -and R5 each represents an alkyl group, such as methyl, ethyl, n-propyl, n-butyl, n-amyl, n-hexyl, n-heptyl, benzyl (phenylmethyl), allyl (vinylmethyl), cyclopentyl, cyclohexyl, etc. (e. g., an unsubstituted or a subsituted alkyl group, especially thosecontaining from 1 to 7 carbon atoms), or an aryl group, such as phenyl, o, m, and p-tolyl, etc. (e. g., a mononuclear aromatic group of the benzene series), provided at least one of the groups selected from R4 land R5 is a pyridyl or quinolyl group as definedv above.

The preparation of the compounds represented by Formula V above requires, in addition to the compounds represented by Formulas II and lV above, an intermediate selected from those represented by the following general formula:

wherein R4 zand R5 each have the values given above.

The compoundsrepresented by Formula VI above can advantageously beprepared by heating together a compound selected from those represented by the following general formulae:

wherein R4 has the values given above and R6 represents a lower alkyl group, such as methyl, ethyl, etc., together .siat) with a compound selected from those represented by the following two general formulae:

VIII. R5-'NCS and IX. R--NH-CSSRq wherein R5 has the values given above and R7 represents a lower alkyl group, such as methyl, ethyl, etc. The condensation of the compounds of Formula VII with either those of Formula VIII or IX can be carried out at temperatures of about 15G-190 C., or even higher temperatures. The condensation of the compounds of Formula VIIa with either those of Formula VIII or IX can be carried out on a steam bath or at even higher temperatures and the product first obtained is an iminothiohydantoin which must then be hydrolysed by treatment with mineral acid to give the thiohydantoin. The preparation of the compounds of III (or VI) follows the method outlined by Wheeler et al.-J. A. C. S. (1911), vol. 46, pages 456-474, except that heterocyclic intermediates are employed in place of the acyclic or aromatic dithiocarbamates employed by Wheeler et al.

The compounds represented by Formula I (or V) wherein R represents a substituted alkyl group can advantageously be prepared by condensing a compound represented by the following general formula:

wherein R, X, Z and n each`have=the values given above with one of the intermediates represented by Formula I in U. S. Patent 2,186,608, page 1,` column 1, line 42. (D and E of patent being identical to the Q'above.)

The following examples will serve to illustrate the manner of preparing the new merocyanine dyes of my invention, as well as the preparation of the new Z-thiohydantoin intermediates necessary for Vpreparing these new merocyanine dyes.

Example 1.-Ethyl N-(Z-pyrdyDglycne N-(Z-pyridyl)aminoacetonitrile (Bristow, Charlton, Peak and Short, I. Chem. Soc., 1954, 616) (160 g.) was added to a solution of concentrated -sulphuric acid (160 cc.) in 99% ethanol (800 cc.). The wholewas then refluxed for 3 hours on a steam bath and poured on to crushed ice (2 kg). Solid sodium bicarbonate was added to neutralize the acid and the thick oil which separated was taken up in ether, the ethereal solution was dried over anhydrous potassium carbonate and the ether distilled off. The residual oil was distilled and collected at 156-168 C /14 mm. Yield 117 g., 54%. On prolonged chilling at 5 C. it slowly solidified to long asbestos-like needles.

`Ethyl N-(2.pyridyl)glycine (18.0 g., 0.1 mol.) and ethylisothiocyana-te (8.8 cc.; 0.1 mol.) were fused together in an oil bath at `Cqfor v3 hours. The whole solidified on chilling. From isopropanol it formed greenish flakes, M. P. 106 C., in 74% yield. Recrystallized from cyclohexane, a sample, formed almost colorless akes, M. P. 107 C.

Example 3 .-3-n-heptyl-1- (Z-pyridyl) -2-thtz'ohydlmtoin Ethyl N-(Z-pyridyl) glycine (9.0 g.), and n-heptylisothiocyanate (7.85 g.) were fused together .at 150 C. for 7 hours. The whole crystallized on chilling. It was dissolvedin hot .ethanol (5 cc.) chilled and seeded. It (70% yield) formed colorless'lakes, M..P. 70 C., from ethanol.

Example 4 .-3-methyl-1 (Z-pyridyl) -2-th0hydanton Ethyl-N-(2-pyridy1)glycine (25.1 g.) and methylisothiocyanate (10 g.) were fused together at150 C. for

EthylN(2-pyridyl)glycine (13.6 g.) and phenylisothiocyanate 10 g.) were fused together at 150 C. for 3 hours. The whole solidified after 1% hours. From acetic acid it formed black needles, M. P. 186 C.

Ethyl-N-(Z-pyridyl)glycine (13 g.) and cyclohexylisothiocyanate (10 g.) were fused together at 150 C. for 7 hours. The whole solidified on chilling. It (7.8 g., 40%) formed soft White needles, M. P. 174 C., from ethanol.

Example 7.-3-benzyl-1-(Z-pyra'yl) -Z-thiohydan'toin Ethyl N-(2-pyridyl)glycine (8 g.) and ethyl N-benzyldithiocarbamate (10.5 g.) were fused together at 150 C. for hours. Ethanol (10 cc.) was added to the melt. On chilling the thiohydantoin separated as an oil, then i-t solidified. It (9.0 g., 63.5%) formed greenish akes, M. I. 115 C., from ethyl acetate-methanol, then from methanol.

Ethyl-N-(2-pyridyl)glycine (18.6 g.) and allylisothiocyanate (10 g.) were fused together at 150 C., for 2 hours. The thick melt was diluted with isopropanol (5 cc.) chilled and scratched. The required substance crystallized, was collected and Washed with ice-cold isopropanol. It (4.7 g., 36%) formed straw colored needles, M. P. 62 C., from methanol.

CH3 N/ -NHOHr-COzCzHs The method for making the precursor of this compound follows the procedure of Bris-tow et al. (loc. cit.). A mixture of formalin (24 cc.), sodium bisulphite (31.2 g.) and water (60 cc.) was stirred for 30 minutes to dissolve, the temperature rising to 40 C. The solution was then heated to 95 C. and 6-methyl-2-amino-pyridine (32.8 g.) was added and the stirring at 95 C. continued for l hour. A solution of sodium cyanide (30 g.)

in water (60 cc.) was run in over 10 minutes and the heating and stirring continued for 4 hours. The solution and separated salt were cooled, the salt was filtered off and the ltrate extracted with chloroform. The chloroform solution was dried and the solvent distilled to leave a brown oil which solidied on chilling. It (28.2 g.) was added to a cooled solution of concentrated sulphuric acid (24 cc.) in ethanol (120 cc.) and the solution was reuxed for 3 hours on a steam bath. The solution was cooled and poured into ice water (300 cc.). Solid sodium bicarbonate was added to neutralize the acid and the brown oil was taken up in ether. The dried ethereal solution was distilled and the required ester (28.0 g., 48% based on amine) collected at S-162 C./ 12 mm.

BIT

6 Ethyl N (6 methyl-2pyridyl)glycine (10 g.) and ethyli'sothiocyanate (4.5 cc.) were fused together at 150- 155 C. for 6 hours. Methanol (10 cc.) was added and the whole chilled. The buff grains (3.0 g., 25.5%) formed white needles M. P. ca. C. from isopropanol.

Z-aminopyridine (18.8 g., 0.2 mol.), carbon disulphide (12 cc., 0.2 mol.) and triethylamiue (30 cc., 0.2 mol.) were warmed on a steam bath to give a homogeneous layer. After a few minutes it separated into two layers. The flask, fitted with a short air condenser, was then shaken, without further heating, on a mechanical shaker. The lower, orange layer gradually thickened as the upper, almost colorless layer gradually disappeared. After ca. 11/2 hours (this time varies with the shape of the ask, violence of agitation and batch size) the whole suddenly solidified. The reaction was slightly exothermic. The contents of the flask were ground to a powder, washed wi-th ether, and collected. Yield 49.0 g. (90.5%) of bright yellow crystals. A sample from ethanol formed lemon yellow plates, M.. P. 84-85" C. (decomp. to 2-aminopyridine, carbon disulphide and triethylamine) Example 12.-Methyl N-(2-pyridyl)dthocalrbamate Nnossorn N The above salt of Example 11 (54.2 g.) was covered with ethanol cc.) and methyl iodide 13 cc.) was added. A slightly exothermic reaction followed as the salt gradually dissolved. The solution was stood for l hour. The required ester had partly crystallized and this was completed by the gradual addition of water. After chilling overnight, the crystals were collected, washed with water, air dried and recrystallized from benzene-light petroleum. They (27 g., 73.5%) formed lemon spears, M. P. 91 C., after a second recrystallization from ethanol.

Example 13.-Ethyl N-(Z-pyljdyl)dthiocarbamczfe Triethylammonium N (2 pyridyl)dithiocarbamate (54.2 g.) was covered with ethanol (150 cc.) and ethyl bromide (16 cc.) was added and the Whole warmed to 5 0 C. The solid dissolved and the solution was set aside for 1 hour. Water (250 cc.) was run in and the oil which precipitated slowly solidified. It was collected and washed with aqueous ethanol (1:1). It (28 g., 71%) formed tine, lemon yellow needles after recrystallization from cyclohexane, then from ethanol, M. P. 64 C.

Example 14. 1-phenyl-.-(Z-pyrdyl) -2-lhiohydanlion Ethyl N-phenylaminoacetate (10 g.) and methyl N-(2-pyridyl)dithiocarbamate (10.2 g.) were fused together at 145-150 C. for 2O minutes. The whole had then solidified. It was dissolved in ethanol (500 cc.) and chilled. It (7.0 g., 47%) formed soft, cream needles, M. P. 190 C., after one furthe;` recrystallization from ethanol, t

Example 15.-1-n-heptyl-.-(Zpyridyl) -Z-thohydantoin Ethyl N-(2-pyridyl)aminoacetate (9.0 g.) and methyl N-(Z-pyridyl)dithiocarbamate (9.2 g.) were fused together at 1404145" C. for 2 hours. Ethanol (10 cc.) was added to the hot melt. The yrequired substance crystallized on cooling. It (9.0 g., 67%) formed soft, butt needles, M. P. 173 C., from ethanol.

Example 17. Tretliylammonum N-(3-pyridyl)dilhocarbamate 3aminopyridine (5.'0 g.), carbon disulphide (3.2 cc.) and triethylamine (8 cc.) were warmed to vmelt and shaken mechanically for 6 hours. Reaction was rapid to give a cake of crystals. The surface liquor was decanted and the crystals washed with ether. They were then dissolved in hot ethanol l cc.) and ether was added to give a crystalline meal. The salt (6.1 g., 42.5%) formed yellow prisms M. P. 87 C. (effervescence), from ethanolether.

Example l8.-Metl1yl N(3-pyrdyl) dthiocarbamate Triethylammonium N (3 pyridyDdithiocarbamate (6.1 gf), ethanol (25 cc.) and methyl iodide (1.5 cc.) were mixed and shaken. The solid dissolved with a mildly eXothermic reaction. After 15 minutes, water was added slowly to give a solid cake of white needles. It (97.5%) formed glossy white akes, M. P. 13S-136 C., from benzene. On fusing at 145 C./10 mm. methanethiol was evolved and i3-pyridyl isothiocyanate distilled. Colorless oil, b. p. 104 C./l4 mm., 228C./765 mm. This can be used instead of its precurser in the formation of thiohydantoins.

Example 19.Trethylammonim1z N-(6-merhyl-2-pylidyl) dthocarbamate 2-amino-6-methylpyridine (21.6 g.)7 triethylamine (30 cc.) and .carbon disulphide (15 cc.) were warmed to give a single phase and then shaken mechanically for 20 hours. A second phase separated after 5() minutes. The solid cake of crystals was ground under ether and vacuum dried. The salt (48.5 g., 85% vformed yellow aggregates, M. P. 76 C., from methanol-ether. Example 20.-Methyl N-(6-methyl-2-pyridyl)dithocarbamate Proceeding as in Example 19, the solid cake of salt was ground to a powder, suspended in ethanol (100 cc.) and treated with methyl iodide. The flask and contents were shaken until the salt had dissolved and set aside for -1 8 hour. Water wasthen added to give the required crystalline ester. vIt wasy collected, washed with water then with light petroleum. 'Itf(28.0 g., 71%) formed pale yellow plates, M. P. 89-90 C., from methanol.

Example 21.-Triethylamm0nium N-(4-'methyl-2-pyridyl)dthiocarbamate Prepared as for iExample `19, the required salt only crystallized afterdissolving the thick orange oil resulting from the reaction,iin a ylittle methanol and running in ether. It formed orange akes, M. P. 76 C.

Example :ZZ-Methyl N-(4-methyl-2-pyridyl)alithiocar- Y Vbamate `Proceeding as AinEXample 21, the crude orange tarot' the trie'thylammonium salt was ldissolved in Vmethanol cc.) and treated with methyl iodide (30 cc.). After 1 hour, water was run in to-gve a mass of crystals. The ester (775.6 g., 76%) formed pale yellow needles, M. P. lOl-102 C., from methanol.

Example 23.--Triezhylammonium N-(3-qu1'n0ly'l)dithiocarbamate 3-aminoquinoline (5.0 g.) was dissolved in dioXan (l0 cc.) carbon disulphide (2.2 ce.) and triethylamine (5.5 cc.) were added and the solution kept at 20-25" C. for 20 hours. A solid cake of yellow crystals had then separated. `It'was ground under ether and collected. lt (97% yield) formed pale yellow prisms, M. P. 89 C. (dec.) from ethanol-ether.

Example 24.--Metl1yl N-(3-q1a'n0lyl)dthiocarbamate Triethylammonium N (3 quinolyl)dithiocarbamate (10.5 g.) was covered with methanol (35 cc.) and methyl iodide (2.1 cc.) was added. On shaking the flask, the salt dissolved and the ester separated as white needles, the whole solidifying. It (6.95 g., 87% 'formed pale yellow needles, M. P. 137-l38 C., from ethanol.

Example 25.--1-ethyl-S-(2-pyrdyl)-2-thohydanton O-r It .e

H2O o=s \l/ CzH Ethylaminoacetonitrile (4.2 g.) and methyl N-(Z-pyridyl)dithiocarbamate (9.2 g.) were heated together on a steam bath for 1 hour. The orange tar was dissolvedin SN-hydrochloric acid by heating on a steam bath for l hour. The solution was diluted with water (100 cc.) and basil-led with ammonia. The resulting orange grains (10.2 g.) were slurried in ethanol, collected and washed with ethanol. They (5.6 g.) were dissolved in boiling benzene (50 cc.), the solution was chilled overnight and the white crystals ltered off and discarded. The filtrate was then concentrated to 20 cc. and the required `substance precipitated by the addition of light petroleum (60 cc.). The required thiohydantoin (2.2 g., 20%) formed fawn needles, M. P. 132 C., from benzene.

Ethyl N-(2-pyrdyl) glycine (9.0 g.) and methyl N-(3- pyridy1)dithiocarbamate (9.2 g.) were fused together at 140 C. for 2 hours. The solid reaction product was ground under ethanol. It (9.8 g., 72.5%) formed soft, light brown needles, M. P. 170-171" C., from ethanol.

Ethyl N-(2-pyridy1) glycine (9.7 g.) and methyl N-(6- methyI-Z-pyridyl)dithiocarbamate (10.7 g.) were fused together at 140 C. for 2 hours. Ethanol (10 cc.) was added to the melt and the solution was chilled to crystallize. It (10.4. g., 73%) formed almost colorless needles, M. P. 146-147 C., from ethanol.

This compound was prepared in a similarway to that of Example 27 in 57% yield. It formed butt needles, M. P. 151 C., from ethanol.

lzydantoz'n Ethyl N(2pyridyl) glycine (4.5 g.) and methyl N(3 quino1y1)dithiocarbamate (5.85 g.) were fused together at 150 C. for 30 minutes. The resulting solid was ground under ethanol, dissolved in boiling benzene, filtered from yellow grains and the solution was concentrated. It (5.0 g., 62.5%) formed glossy, pale green akes, M. P. 204 C., from ethanol.

added, the solution cooled and scratched.

4-aminopyridine (4.8 g.) was dissolved in hot pyridine (30 cc.), cooled at 25 C. and carbon disulphide (3.3 cc.) and triethylamine (8 cc.) were added. After 3-4 hours, yellow crystals separated. After standing for 20 hours, ether cc.) was added and the crystals collected and washed with cold ethanol. lt (6.9 g., 51%) formed orange Hakes, M. P. 141 C.

Example 32.-Methyl N-(4-pyrdyl)dtllocarbamate The product of Example 31 (13.5 g.), methanol (50 cc.) and methyl iodide (3.5 cc.) were warmed to dissolve and allowed to cool. After 1 hour, water (200 cc.) was added to give an oil which slowly crystallized. From a little ethanol it (6.8 g., 74%) formed pale yellow prisms, M. P. 142l44 C.

2-2-acetanilidovinylbenzoxazole ethiodide (2.2 g.), 3- ethyl-l-(2-pyridyl)-2-thiohydantoin 1.1 g.), ethanol (10 cc.) and triethylamine (0.8 cc.) were relluxed together for 15 minutes on a steam bath. The dyel was collected after chilling. Yield 1.15 g. (78.5%). It formed red needles, M. P. 216217 C., from ethanol. It sensitized a silver iodobromide and a silver chlorobromide emulsion strongly with peaks at 550 mu.

2-2'-acetanilidovinylthiazoline methiodide- (3.9 g.), 3- ethy1-1(2pyridyl)-2-thiohydantoin (2.2 g.), ethanol (15 cc.) and triethylamine (1.5 cc.) were heated together for 15 minutes on a steam bath. Ethanol (10 cc.) was The dye (1.35 g., 39%) formed rust needles, M. P. ISO-182 C., after recrystallizing first from benzene-light petroleum and then from ethanol. It sensitized silver iodobromide and chlorobromide emulsions strongly with peaks at 530 mu,

ass-9,4055

. Example 35.--3fethyl-5-(3ethyl-4,5-diplzenyloxazolin2 ylidene-ethylidene) -1-(2-pyridyl) *IZ-thiohydantoin sulphonate (2.7 g.), 3-etl1yl-1-(2-pyridy1)f2 thiohydantoin (1.1 g.), ethanol cc.) and triethylamine (2.5 cc.) were heated on a steam bath until vthe alcohol boiled. Acetic anhydride (l ce.) was added and the whole was reuxed for 5 minutes. After chilling overnight, fthe red crystals (1.8 g., 73%) were collected. They were recrystallized from benzene-light petroleum, .then from ethanol and formed red needles, M. P. 23S-237 C. It sensitized a silver chlorobromide or iodobromide emulsion with peaks at 560 mu.

12 2 acetanilidovinylnaphtho 1',2 4,5 oxazoleethiodide (2.4 g.) was treated as in ExampleV 36m-'give 1.15 g. (52%) vdye which formed orange-redneedles, M. P. 176-177 C., from pyridinethanol. 21e-sensitized silver c hlorobrornide or iodobromide emulsions strongly with peaks at 565 mu.

Cit

C C\ /'(i3=S N blt CHI i 2 methylthiobenzothiazole metho--p toluenesulphonate (1.85 g.), 3-ethyl-l-(2-pyridyl)-2-thiohydantoin (1.1 g), ethanol (10 cc.) and triethylamine (0.8 cc.) were retiuxed together for 15 minutes. The dye separated rapidly. From benzene-light petroleum, then from ethanol it (1.55 g., 84%) formed soft, yellow akes, in. p. 241 C. ItV sensitized a silver chloride emulsion strongly with a peak-at 440 mu.

N l (i) :H5

2-4'acetanilidobuta1,3dienylbenzothiazole ethiodide (2.4 g.), 3-ethyl-1-(2-pyridy1)-2-thiohydantoin (1.1 g.), ethanol (10 ce.) and triethylamine (0.8 cc.) were reuxed together for 15 minutes. The dye which separated on chilling was extracted with boiling benzene, the benzene extract was filtered and concentrated until crystallization set in. AAn equal volume ,OLlight petroleum was addedto give 1.6 g. (73.5%) dye. llt formed soft, blue needles, M. P. 2434245" v C., from pyridine-ethanol.

It sensitized a silver iodobromide emulsion strongly with a peak at 685 mu and a silver chlorobromide with a peak at 690 mu.

2 4 acetanilidobuta 1" 3" dienylnaphtho 2,1 4,5-thiazole ethiodide (118g), 3-ethyl-1-(2p-pyridyl)-2- thiohydantoin (0.8 g.)pyridine (5 ce.) and triethylamine (0.7 cc.) were reiluxed on a gauze for 30 minutes. Methanol (30 cc.) was added, the mixture was chilled overnight and the dye collected. The latter was extracted with benzene, the extracts filtered, concentrated to 15 cc. and methanol (30 cc.) added. The dye (0.95 g., 54.5%) which crystallized formed glittering green flakes, M. P. Z50-251 C., from-benzene-ethanol.

It `sensitized. a silver chlorobromide strongly with a peak at 690 mu and a silver iodobromide emulsion with a peak at 685 mu.

I CzHI 22-acetanilidovinylbenzoxazole ethiodide (2.2` g.), 3- n-heptyl1(Z-pyridyl)-2-thiohydantoin (1.5 g.), ethanol cc.) and triethylamine (0.8 cc.) were reiluxed together for minutes. On chilling overnight, the dye slowly crystallized. 1t (1.45 g., 62%) formed soft orange needles, M. P. 1Z0-121 C., from isopropanol.

It sensitized a silver iodobromide emulsion strongly with a peak at 540 mu and a silver chlorobromide emulsion with a peak at 550 mu.

2 2 acetanilidovinylnaphtho 2,1 4,5 oxazole ethiodide (2.4 g.), 3-hepty1-1-(2pyridyl)2fthiohydantoin (1.45 g.), pyridine (10 cc.) and triethylamine (1 cc.) were relluxed together on a gauze for minutes. Ethanol (25 cc.), then water (25 cc.) were added to precipitate the dye as a tar which solidified on standing overnight. It was collected, air dried and extracted with benzene. The benzene was concentrated to 10 cc., ethanol (25 cc.) was added and the solution concentrated to 15 cc. The dye separated on chilling. It (1.7 g., 66.5%) formed soft red needles, M. P. 131-133 C., (soft at 105 C.) after 'recrystallization from benzeneethanol, then from ethanol.

It sensitized a silverchlorobromide or iodobromide emulsion strongly with peaks at 570 mu.

This dye was obtained in a similar manner to EX- ample 43, in 56.5% yield as soft red needles, M. P. l36-138 C. from ethanol.

It sensitized silver chlorobromide or iodobromide emulsions strongly with peaks at 570 mu.

2-4-acetanilidobutal,3dienylbenzothiazo1e ethiodide (2.4 g.), 3nheptyl-1-(Z-pyridyl)-2thiohydantoin (1.45 g.), pyridine (10 cc.) and triethylamine (0.8 cc.) were refluxed together for 30 minutes. Methanol (40 cc.) was added and the solution was chilled overnight. The dye (48% yield) formed blue needles, M. P. 149-151rl C. from benzene-cyclohexane. It sensitized a silver chlorobromide emulsion strongly with a peak at 680 mu.

If I CiHs This dye was obtained similarly to Example 46, in 31% yield, as soft bronze threads, M. P. 161 C. from pyridinemethanohthe threadsgturned green on drying.

It-y sensitized a silver chlorobromide emulsion strongly with a peak at 710 mu.

2 4 acetanilidobuta l`,3"-dienylnaphtho-l,2-4,5 thiazole ethiodide (5.26 g.), 3-allyl-1-(2-pyridyl)2thio hydantoin (2;35g.), pyridine (15 ce.) aud triethylamine (1.5 cc.) were reuxed for minutes. Ethanol (40 cc.) was added and the dye collected after chilling. It Was extracted with benzene,V the` benzene'extracts were concentrated andthe dye wasbrought to crystallization `by the 4addition of` ethanol. It (0.8 g., 16.1%) formed softv green threads, M. P.'250 C., from pyridine-methano1.

It sensitizeda silver chlorobromide emulsionstrongly withY a. peakat 7110 mu.

I l l The dye was obtained as in Example 48 but using 3- rnethy1l(l-pyridyl)-2-thiohydantoin (2.1 g). It (1.1 g., 23.4%) formed soft, green needles, M. P. 258 C., from pyridine-methanol.

It sensitized a silver chlorobromide emulsion strongly with a peak at 700 mu.

This dye was obtained as in Example 48 but using 3- phenyl-1-(2-pyridyl)-2-tl1ohydantoin (2.7 g.). The crude dye was extracted in a Soxhlet apparatus with xylene to give a 1.8 g. (33.8%) yield. It formed green threads, M. P. 268 vYC., from pyridine-methanol.

It sensitized a silver chlorobrornide emulsion strongly with a peak at 710 mu.

Example 51 .-3 -benzyl-5 (3-ethylbenz0xaz0ln-Z-y ldeneethylidene) -1-(2-pyridyl) -2-tl10hydantoin 2-2acetanilidovinylbenzoxazole ethiodide (2.15 g.), 3-benzyl-l-(2-pyridyl)f2-thiohydantoin (1.4 g.), ethanol (l5 cc.) and triethylamine (0.8 cc.) were reuxed together for 15 minutes. The dye was collected from the chilled solution. It (1.95 g., formed red needles, M. P. 214 C. from benzene ethanol. It sensitized a silver chlorobromide emulsion strongly with a peak at 550 mu.

2 2" acetanilidovinylnaphtho 2,1 4,5 oxazole ethiodide (4.85 g.), l-n-heptyl-S-(Z-pyridyl)-2-thiohydantoin (2.9 g), pyridine (15 cc.) and triethylamine (1.5 cc.) were reiiuxed together for 30 minutes. Puried as in Example 52 it (1.8 g., 35%) formed magenta needles, M. P. 192 C., from benzene-ethanol.

It sensitized aV silver chlorobromide emulsion strongly with a peak at 575 mu.

2-4acetanilidobuta1,3dienylbenzothiazo1e ethiodide (4.76 g.), 1-heptyl-3-(2-pyridyl)-2-thiohydantoin, pyridine (20 cc.) and triethylamine were refluxed together for 30 minutes. The dye was isolated and purified as for Example 52. It (1.5 g., 30%) formed tiny brown needles, M. P. ISU-182 C., from benzene-methanol.

It sensitized a silver chlorobromide emulsion strongly with a peak at 690 mu.

thz'ohydantol'n Was obtained 22% yield in a manner analogous to its isomer of Example 52 and formed soft green needles, M. P. 243 C., from benzenefethanol.

It sensitized a silver chlorobromide emulsion strongly with a peak at 710 mu.

Was obtained similarly from 2,4-acetanilidobuta-1, 3-dieny1naphtho2,14,5-thiazo1e ethiodide (5.26 g.) and 1-phenyl-3(2-pyridyl)2thiohydantoin (2.7 g.). The crude dye was extracted with benzene in a Soxhlet and obtained (1.8 g., 34%) as dull green threads, M. P. 261 C., from pyridine-methanol.

It sensitized a silver chlorobromide emulsion strongly with a peak at 710 mu.

2-4acetanilidobuta1,3dieny1naphtho 2,14,5- thiazole ethiodide (2.2 g.), 1-ethyl-3-(2-pyridyl)-2-thiohydantoin (0.9 g.), pyridine (10 cc.) and triethylamine (0.6 cc.) were reuxed together for 30 minutes, pooled and methanol (30 ce.) was run in. After `chilling overnight the dye was collected, Washed with methanol, dried and extracted with benzene. The benzene solution was evaporated and the dye (1.2 g., 31%) recrystallized fromA pyridine-methanol. 259 C. It ybromide emulsion strongly with Amm 700 mu.

It formed soft green threads, M. `P.

Obtained as for the dye of Example 57, but using 1-(2- pyridyl)-3-(3-pyridyl)-2-thiohydantoin, it formed soft, green needles, M. P. 275 C., in 43% yield.

It sensitized a silver chlorobromide emulsion strongly with Amex, 695 mu.

2-2-acetanilidovinylbenzoxazole ethiodide 1.5 g.), 1-(2-pyridyl)3-(6methyl2-pyridyl) 2 thiohydantoin (0.95 g.), ethanol (10 cc.) and triethylamine (0.6 cc.) were reuxed for 30 minutes. The dye crystallized slowly on chilling. It is a mixture yof two dyes. It was dissolved in benzene cc.) and concentrated to 40 ce. Dye A sensitized a. silver iodobromide or` chloro-` 2-2-acetanilidovinylbenzoxazole ethiodide (1.45 g), 1 (2 pyridyl) 3 (3 quinolyl) 2 thiohydantoin (1.1 g.), ethanol (25 cc.) and triethylamine (0.5 cc.) were refluxed for 15 minutes. The dye separated rapidly and it (2.25 g., 76%) formed soft, orange threads, M. P. 258 C., from pyridine-ethanol. lt sensitized a silver iodobromide emulsion strongly with Amm 540 mu.

Obtained as the dye of Example 60 but using 1-(2- pyridyl) 3 (4 methyl 2 pyridyl) 2 thiohydantoin, it (79% yield) formed hard orange needle rosettes from benzene, M. P. 110 C. (effervescence). lt sensitized a silver iodobromide emulsion strongly with AMK 540 Inu.

cc.) and triethylamine (0.8 cc.) were reiluxed for 30 minutes, cooled and methanol (50 cc.) and water (50 20 cc.) were added. The dye was collected after chilling overnight, air dried and extracted with benzene and the benzene solution was concentrated to 30 cc. The dye which separated (0.5 g.) formed green crystals M. P. 204 C., from pyridine-ethanol. It `sensitized a silver chlorobromide emulsion strongly with xmax, 710 mu.

Obtained similarly to Example 63 from the higher M. P. 1,3 di (6 methyl 2 pyridyl) 2 thiohydantoin, it (28.5%) formed dark green needles, M. P. 213 C. It sensitized a silver chlorobromide emulsion With Amm.. 690 mu.

2 4" acetanilidobuta 1",3 dienylnaphtho 2',1' 4,5-thiazole ethiodide (2.7 g.), 3-ethy11'(6-metl1yl2 pyridy1)2thiohydantoin (1.2 g.), pyridine (15 cc.) and triethylamine (0.8 cc.) were reuxed together for 30 minutes. Ethanol cc.) was added and the whole chilled overnight. The crystals were air dried and the required dye extracted with benzene. The benzene was distilled olf and the residue (0.75 g., 29.5%) recrystallized twice from pyridine-methanol. It formed green ilakes, M. P. 262 C. (decomp.). It sensitized a silver chlorobromide emulsion strongly with am, 700 mu.

I have also found that dyes corresponding to those of Formula V above wherein either R4 `or R5 represents a thiazyl group can be prepared and that these dyes likewise sensitize photographic silver halide emulsions. The following examples illustrate the preparation of the necessary intermediates and these new merocyanine dyes.

Example 66.-Trelhylamm0nam N 2 thazolyldithiocarbamate Example 67.-Methyl N-Z-thiazolyldthocarbamate The product of Example 66 (15.0 g.) was finely ground and warmed with methanol cc.) and methyl iodide (3.5 cc.). The salt dissolved as the ester crystallized. After 2 hours, the thick meal of crystals was collected 21 and washed with water, then ethanol. It (9.3 g., 90.5%) formed straw needles, M. P. 175-176" C., from ethanol.

Example 68.-1-methyl-3-(Z-thiazolyl) -2-thiohydantoin Potassium hydroxide (5.6 g.) was dissolved in water (25 cc.) and N-methylglycine hydrochloride (6.3 g.) was added. The product of Example 67 (9.5 g.) and ethanol (50 cc.) were added and the whole was `reuxed on a steam bath for 20 hours. After cooling the solid was iiltered off and discarded. The filtrate was acidiied with acetic acid, the small amount of tar was removed and the liquor concentrated to 75 cc. On chilling a tar separated which slowly crystallized. It (1.9 g., 18%) formed pink needles, M. P. 133 C., from ethanol.

Proceeding as in Example 68 but using N-ethylglycine hydrochloride in equivalent amount, the product (28% yield) formed pink needles, M. P. 176-177 C., from ethanol.

Example 70.-- (3 ethylnaphtho 2',] 4,5 thazo- 2 4 acetanilidobutadienylnaphtho 2,1' 4,5 thiazole ethiodide (2.7 g.), the product of Example 68 (1.05 g.), pyridine cc.) and triethylarnine (0.8 cc.) were refluxed together for '1/2 hour. Ethanol (50 cc.) was added and the blue solution chilled overnight. The dye was air dried and extracted in a Soxhlet apparatus with benzene. The solvent benzene was removed and the dye (1.25 g., 52.5%) recrystallized from pyridineethanol as dark green threads, M. P. 285 C.

As shown in a number of the above examples, the dyes of my invention are particularly useful in sensitizing photographic silver halide emulsions, serving to alter the sensitivity thereof in a most useful manner. Sensitization by means of my new dye is, of course, directed primarily to the ordinarily employed, gelatinosilver-halide, developing-out emulsions. The dyes are advantageously incorporated in the washed, finished emulsion and should, of course, be uniformly distributed throughout the emulsion. In the preparation of photographie emulsions containing my new dyes, it is only necessary to disperse the dyes in the emulsions. The methods of incorporating dyes in emulsion are simple and well known to those skilled in the art of emulsion making. It is convenient to add the dyes from solutions in appropriate solvents. The solvent must, of course, be compatible with the emulsion and substantially free from any deleterious effect on the light-sensitive materials. Methanol has proven satisfactory as a solvent for the majority of my new dyes.

The concentration of my new dyes in the emulsion can vary widely, i. e. from about 5 to about 100 mgs. per liter of flowable emulsion. The concentration of the dye will vary according to the type of light-sensitive material in the emulsion and according to the eiiects desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making the ordinary tests and observations customarily used in the art of emulsion making.

To prepare a gelatino-silver-halide emulsion sensitized with one of my new dyes, the following procedure is satisfactory: A quantity of the dye is dissolved in methyl alcohol or other suitable solvent and a volume of this solution (which may be diluted with water) containing from 5 to 100 mgs. of dye is slowly added to about 1000 cc. of a gelatino-silver-halide emulsion, with stirring. Stirring is continued until the dye is uniformly distributed throughout the emulsion. With most of my new dyes, 10 to 20 mgs. of dye per liter of emulsion sufiices to produce the maximum sensitizing effect with the ordinary gelatinesilver bromide (including bromiodide) emulsions. With line-grain emulsions, which include most of the ordinarily employed gelatino-silver-chloride emulsions, somewhat larger concentrations of dye may be necessary to secure the optimum sensitizing effect.

The above statements are only illustrative and are not to be understood as limiting my invention in any sense, `as it will be apparent that my new dyes can be incorporated by other methods in many of the photographic -silver halide emulsions customarily employed in the art.

For instance, the dyes can be incorporated by bathing a plate or film upon which an emulsion has been coated, in the solution of the dye, in an appropriate solvent. Bathing methods, ordinarily.

Photographic silver halide emulsions which can advantageously be sensitized by means of the new dyes of my invention comprise the customarily employed gelatinesilver-chloride, gelatino-silver-chlorobromide, gelatinesilver-bromide,. and gelatina-silver-bromiodide develop-,

ing-out emulsions. p

Photographic silver halide emulsions, such as those listed above, containing the sensitizing dyes of my invention can also contain such addenda as chemical sensitizers, e. g., sulfur sensitizers (e. g., allyl thiocarbamide, thiourea, allylisothiocyanate, cystine, etc.), various gold compounds (e. g., potassium chloroaurate, aun'c trichloride, etc.) (see U. S. Patents 2,540,085; 2,597,856 and 2,597,915), various palladium compounds, such as palladium chloride (U. S. 2,540,086), potassium chloropalladate (U. S. 2,598,079), etc., or mixtures of such sensitizers; antifoggants, such as ammonium chloroplatinate (U. S. 2,566,245), ammonium chloroplatinite (U. S. 2,566,263), benzotriazole, nitrobenzimidazole, 5-nitroindazole, benzidine, mercaptans, etc. (see Mees--The Theory of the Photographic Process, Macmillan Pub., page 460), or mixtures thereof; hardeners, such as formaldehyde (U. S. 1,763,533), chrome alum (U. S. 1,763,533), glyoxal (U. S. 1,870,354), dibroacrolein (Br. 406,750), etc.; color couplers, such as those described in U. S. Patent 2,423,730, Spence and Carroll U. S. Patent 2,640,776, etc.; or mixtures of such addenda. Dispersing agents for color couplers, such as those set forth in U. S. Patents 2,322,027 and 2,304,940, can also be employed in the above-described emulsions.

The accompanying drawing further illustrates my invention. Each ligure is a diagrammatic reproduction of a spectrogram showing the sensitivity of an ordinary gelatino-silver-chlorobromide emulsion containing one of my sensitizing dyes. In Figure 1, the curve depicts the sensitivity of an ordinary gelatino-silver-chlorobromide emulsion containing 5 (3 ethylnaphtho 2,1 4,5 thiazolin 2 ylidene buta 2,4" dienylidene) 1 nheptyl-3-(2-pyridyl)-2-thiohydantoin. In Figure 2, the

however, are not to be preferred' curve depicts the sensitivity of an ordinary gelatino-silverchlorobromide emulsion containing -(3-ethylbenzothiazolin 2 ylidene buta 2',4' dienylidene) 1- n-heptyl-3-(2-pyridyl)2thiohydantoin. In Figure 3, the curve depicts the sensitivity of an ordinary gelatinesilverfchlorobromide emulsion containing 5-(3-ethylnaphtho 2,1 4,5 thiazolin 2 ylidene buta- 2.,4 dienylidene) 1 phenyl 3 (2 pyridyl) 2- thiohydantoin. The sensitometric measurements for a somewhat similar gelatino-silver-chlorobromide emulsion for these dyes are given in Examples 46, 54 and 56, respectively.

What I claim as my invention and desire secured by Letters Patent of the United States is:

1. A photographic silver halide emulsion sensitized with a compound selected from those represented by the following `general formula:

N f R-i-oH -=o11).1-`o =L-L)14:6 o=o wherein R represents an alkyl group, d represents a positive integer of from 1 to 3, n represents a positive integer of from 1 to 2, L represents la rnethine group, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, and Q represents the non-metallic atoms necessary to complete a heterocyclie nucleus of the 2-thiohydantoin series, said heterocyclic nucleus of the 2-thiohydantoin series having a pyridyl or quinolyl substituent attached to at least one of the nitrogen atoms thereof.

2. A gelatino-silver-halide emulsion sensitized with a compound selected from those represented by the following general formula:

wherein R represents an alkyl group of theA formula CmHzmJfl wherein m represents a positive integer of from 1 to 4, n represents a positive integer of from 1 to 2, d represents a positive integer of from l to 3, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzthiazole series, those of the naphthothiazole series, those of the thianaphtheno-7,6,4,5-thiazole series, those of the oxa- Zole series, those of the benzoxazole series, those of the naphthoxazole series, those of the selenazole series, those of the benzselenazole series, those of the naphthoselena- Zole series, those of the thiazoline series, those 'of the 2-quinoline series, those of the 4wquinoline series, those of the 1isoquinoline series, those of th;` 3,3-dialkylindolenine series, those of the Z-pyridine series and those of the 4-pyridine series, R4 and R5 each represents a member selected from the group consisting of an alkyl group containing fromv 1 to 7 carbon atoms, a mononuclear aromatic group of the benzene series, a pyridyl group, and a quinolyl group, at least one of the 4groups selected from the group consisting of R4 and R5 being a member selected from the group consisting of a pyridyl group and a quinolyl group.

3. A gelatino-silver-halide emulsion as deiined in claim 2 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzthiazole series.

4. A gelatino-silver-halide emulsion as defined in claim 2 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzoxazole series.

5. A gelatine-silver-halide emulsion as defined in claim 2 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series.

6. A gelatino-silver-halide emulsion as defined in Claim 2 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus ofy the'naphthoxazole series.

7. A gelatino-silverh-alide emulsion as defined in claim 2 wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the thiazoline series.

8. A photographic gelatino-silver-halide emulsion sensitized with a compound represented by the following for- 9. A photographic gelatin-silver-halide emulsion sensitized with a compound represented by the following for- 10. A photographic gelatine-silver-halide emulsion sensitized with a compound represented by the following formula:

o=oNC E 40 I i s C=OHCH=CHCH=C\ =S N f l? I 02H5 N .5

11. A photographic gelatino-silver-halide emulsion sensitized with a compound represented by the following formula:

0:(1--N--C7H15 G=CHOH=C G=s \N/ llt, 1 02H5 12. A photographic gelati-no-silver-halide emulsion sensitized with a compound represented by the following for- 25 26 References Cited in the le of this patent 2,340,882 Kendall Feb. 8, 1944 UNITED STATES PATENTS 2,353,164 Kendall et al July 11, 1944 2,166,736 White et a1 July 1s, 1939 OTHER REFERENCES 2,263,749 White et al NOV. 25, 1941 5 Chemical Abstracts 16:3101. (Copy in S. L.) Ab- 2,320,654 Riester June 1, 1943 stnact of Brit. Med. Journal, 1922, I, S14-515. 2,322,015 Hamer et al 111116111943 Chemical Abstracts 19:530. (Copy in S. L.) Ab- 2,338,782 Riester Ian. 11, 1944 straat of Proc. Roy. Soc. London, 96B, 317-333, 1924. 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION SENSITIZED WITH A COMPOUND SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 